1. Field of the Invention
The presently disclosed subject matter relates to preventing or mitigating formation of metal sulfide scales during oil and gas production.
2. Description of Art
Iron sulfide (FeS) is a form of metal sulfide that is often present in sour systems due to the reaction between iron and hydrogen sulfide. The iron sulfide can form scales which accumulate over time in production tubing, pipelines, heat exchangers, valves and other equipment.
There are a number of problems associated with iron sulfide scales. For example, the scaling can lead to bacterial growth and corrosion. It can also cause flow assurance problems as scale builds up in the equipment. Additionally, iron sulfide can be converted into toxic hydrogen sulfide (H2S) upon exposure to acids. Dry iron sulfide is pyrophoric and ignites spontaneously when exposed to air. Further, iron sulfide at the oil-water interface can stabilize emulsions and interfere with downstream separation processes. Also, inhibition chemistry for iron sulfide is often based on toxic acrolein chemistry which presents a significant danger to both human health and the environment.
Thus, prevention or mitigation of metal sulfide scale, and in particular iron sulfide scale, during oil and gas production is desired.